Running 12.04. I can manually suspend the system and wake it up again, but I can't get it to suspend on inactivity automatically.
I have it set to "Suspend when inactive for" 10 minutes in systems settings > power. It just blanks the screen, but does not suspend.
Info as requested. Left system untouched at 18:30 with suspend set to 10 minutes.
kern.log and dmesg had nothing new in them.
sys.log had these extra lines
Aug 23 18:34:26 Ubuntu-desktop AptDaemon: INFO: Quitting due to inactivity
Aug 23 18:34:26 Ubuntu-desktop AptDaemon: INFO: Quitting was requested
Aug 23 18:39:01 Ubuntu-desktop CRON[3228]: (root) CMD ( [ -x /usr/lib/php5/maxlifetime ] && [ -d /var/lib/php5 ] && find /var/lib/php5/ -depth -mindepth 1 -maxdepth 1 -type f -cmin +$(/usr/lib/php5/maxlifetime) ! -execdir fuser -s {} 2>/dev/null \; -delete)
Well, I finally managed to get it to suspend fully on inactivity.
In addition to System Settings > Power set to turn off after 10 minutes, I had to ALSO set System Settings > Brightness and Lock to turn off the screen after 10 minutes.
Surely if these 2 settings are dependent on each other they should be together in one section of System Settings? The way they interact seems wrong, and the Systems Settings > Power section doesn't hint or warn that it can't be set independently.
Had same issue on 12.04, fixed by setting org.gnome.settings-daemon.plugins.power
sleep-display-batteryto a value lower than the value ofsleep-inactive-battery-timeout.